In recent years, actuators using Micro Electro Mechanical Systems (MEMS) have been studied. As the applications of the actuators, optical reflecting elements that scan laser light and project an image on, for example, a screen are being developed. In order to project an image, it is necessary to scan laser light using the optical reflecting element at a high speed by a large deflection angle.
When a movable portion including a reflecting portion of the optical reflecting element is driven at a high speed by a large deflection angle, dust in air may adhere to a portion surrounding the reflecting portion, and contaminates the reflecting portion. The contamination reduces an intensity of the reflected light due to decrease in the reflectance of the reflecting portion, and causes light scattering due to the laser light applied to the contaminated portion, accordingly reducing the brightness of the image and degrading the image.
In order to address these problems, PTL 1 discloses an optical reflecting element in which a reflecting portion is covered with an optical transparent component for preventing the contamination from adhering to the reflecting portion. PTL 2 discloses an optical reflecting element that prevents the contamination from adhering to the reflecting portion by providing a dust adherence portion around the reflecting portion. PTL 3 discloses an optical reflecting element that prevents the contamination from adhering to the reflecting portion by processing the lateral side of the reflecting portion to provide a dust adherence portion. PTL 4 discloses a method for preventing dust from adhering due to charging. This method uses a conductive material having a low resistivity as a transparent overcoat layer of the reflecting portion.